Data reader with front shield coupling structure

ABSTRACT

A data reader may consist of at least a magnetoresistive stack positioned on an air bearing surface. A portion of the magnetoresistive stack may be set to a first fixed magnetization by a pinning structure separated from the air bearing surface by a front shield that is set to a second fixed magnetization by a biasing structure. The front shield may be separated from the biasing structure by a coupling structure.

SUMMARY

A data reader, in accordance with assorted embodiments, has amagnetoresistive stack positioned on an air bearing surface with aportion of the magnetoresistive stack set to a first fixed magnetizationby a pinning structure separated from the air bearing surface by a frontshield. A biasing structure sets the front shield to a second fixedmagnetization that differs from the first fixed magnetization. Acoupling structure separates the front shield from the biasingstructure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block representation of an example data storage systemconfigured and operated in accordance with some embodiments.

FIG. 2 displays a line representation of a portion of an example datareader capable of being used with the data storage system of FIG. 1.

FIG. 3 shows a cross-section view line representation of a portion of anexample data reader configured in accordance with some embodiments.

FIG. 4 illustrates a cross-section view line representation of a portionof an example data reader arranged in accordance with variousembodiments.

FIG. 5 depicts a cross-section view line representation of a portion ofan example data reader configured in accordance with some embodiments.

FIG. 6 is a cross-section view line representation of a portion of anexample data reader arranged in accordance with assorted embodiments.

FIG. 7 shows a cross-section view line representation of a portion of anexample data reader configured in accordance with some embodiments.

FIG. 8 plots an example data reader fabrication routine that may becarried out in accordance with various embodiments.

DETAILED DESCRIPTION

In accordance with the continued goal of increasing data storagecapacity in data storage devices, data access components, such as datareaders and data writers, have reduced magnetic and physical sizes. Byrecessing a portion of a data reader from an air bearing surface (ABS),the practical size of a data reader can be decreased. However, recessingportions of a data reader can induce magnetic volatility in shields thatseparate the recessed portions from the ABS. Thus, various embodimentsare directed to stabilizing portions of a data reader employing arecessed magnetic portion.

In a non-limiting example, a data reader is configured with amagnetoresistive (MR) stack positioned on an air bearing surface and aportion of the MR stack is set to a first fixed magnetization by apinning structure separated from the air bearing surface by a frontshield that is set to a second fixed magnetization by a biasingstructure separated from the front shield by a coupling structure.Currently, there is no adequate integration scheme proven to produce aseamless interface between front and core portions of a shield that areconstructed of similar materials, such as NiFe in permalloycompositions. That is, residue from the recessed pinning structure canremain beneath the front shield, which can result in magneticinstability in the front shield due to a lack of consistent couplingbetween the front and core portions of a reader shield.

The ability to tune the materials, position, size, and number ofconstituent sub-layers allows the coupling structure to provideconsistent coupling between the front and core portions of a shielddespite a reduced physical size of the data reader on the ABS. Suchconsistent coupling can optimize data reader performance by decreasingthe magnetic extent of the MR stack while allowing the recessed pinningstructure to set a reference magnetization in the MR stack.

While a data reader employing a recessed pinning structure can beutilized in an unlimited variety of environments and systems, FIG. 1provides an example data storage system 100 in which a tuned data readercan be commissioned in accordance with some embodiments. Although notrequired or limiting, the data storage system 100 can have one or moredata storage devices 102 that are configured with at least one datastorage means. It is contemplated that various solid-state volatile andnon-volatile memories can be used in a hybrid data storage device.

Assorted embodiments arrange at least one data storage means of the datastorage system 100 as a hard disk drive with at least one transducinghead 104 accessing data bits 106 stored in patterned data tracks 108 ona data storage medium 110. The transducing head 104 can utilize one ormore data writers 112 and data readers 114 to access the data bits 106to store and/or read data from the data storage medium 110 across an airbearing 116. At least one local controller 118, such as amicroprocessor, can control the size of the air bearing 116 on which thetransducing head 104 floats and the position of the transducing head 104by concurrently or successively manipulating the spindle motor 120 ofthe data storage medium 110 and an actuator 122 portion of the datastorage device 102.

The controller 118 can be connected to the various aspects of the datastorage system 100, as shown, to monitor, detect, and control the datastorage environment to provide data access operations. At least onecontroller 118 can be local and incorporated into the data storagedevice 102 and one or more controllers 118 can be remote and connectedto the data storage device 102 via wired or wireless networks 124.Connection to at least one network 124 allows the local controller 118to be utilized individually or collectively with other controlling means126, such as processors, servers, hosts, and nodes, which are notphysically located in or on the data storage device 102.

To increase the data storage capacity of the data storage device 102,the data bits 106 are positioned closer together in data tracks 108 withreduced widths. Such increase in data density causes a data reader tohave a reduced magnetic extent to allow the sensing of individual databits 106. FIG. 2 displays a line representation of a portion of anexample data reader 130 that may be employed in the data storage system100 of FIG. 1 to sense data arranged in high data density environments.The data reader 130 has a magnetoresistive stack 132 disposed betweenfirst 134 and second 136 shields as well as between side shields 138.

The magnetoresistive stack 132 can be separated from the side shields138 by lateral nonmagnetic layers 140 and separated from the first 134and second 136 shields by conductive cap and seed electrode layers,respectively. The magnetoresistive stack 132 may be configured in avariety of different manners to sense data from an adjacent data storagemedium. For example, the magnetoresistive stack 132 may be a spin valve,trilayer lamination without a fixed magnetization, or a lateral spinvalve with a fixed magnetization structure 142 separated from amagnetically free structure 144 by a spacer structure 146, as shown.

Decreasing the shield-to-shield spacing (SSS) 148 of the data reader 130can increase data bit linear resolution, but can correspond withincreased magnetic and thermal volatility that results in degradedperformance. In other words, a small SSS 148 can decrease the magneticextent of the data reader 130, but can also increase the risk ofinadvertent magnetic behavior that can jeopardize the accuracy of databit sensing.

FIG. 3 shows a cross-section view line representation of a portion of anexample data reader 160 arranged in accordance with assorted embodimentsto increase magnetic performance despite a small SSS. The data reader160 has a magnetoresistive (MR) stack 162 disposed between first 164 andsecond 166 shields that define the SSS 168. By recessing a fixedmagnetization reference pinning structure 170 away from an air bearingsurface (ABS), the reference structure 172 of the MR stack 162 can beset to a predetermined magnetization orientation 174 without adding tothe SSS 168.

It is noted that the MR stack 162 is configured as a spin valve in FIG.3 with a magnetically free layer 176 separated from the fixedmagnetization reference structure 172 by a non-magnetic spacer layer178, but such configuration is not required or limiting as lateral spinvalve, trilayer, and abutted junction configurations may be utilized.The reference structure 172 is shown as a lamination of magnetic andnon-magnetic layers, but various embodiments may configure the referencestructure 172 as a single magnetic layer that is set to thepredetermined magnetic orientation 174 by the fixed magnetizationreference pinning structure 170.

By moving the fixed magnetization reference pinning structure 170 awayfrom the ABS, the SSS 168 is reduced, but the front shield portion 180of the second shield 166 is vulnerable to unpredictable magneticvolatility. The lateral alignment of the fixed magnetization referencepinning structure 170 and the front shield portion 180 along the X axiscan restrict the physical connection of the front shield portion 180with the second shield core 182, as indicated by segmented seam 184.

That is, construction of the front shield portion 180 atop the secondshield core 182 can result in a partial or complete seam 184 that caninhibit coupling between the core 182 and front shield portion 180. Forexample, residual dielectric material from the seed layer 186 of thepinning structure 170 can be present along seam 184, which degradescoupling between the front shield 180 and core 182 portions of the firstshield 164. Thus, recessing the fixed magnetization reference pinningstructure 170 can decrease SSS 168 at the expense of increased magneticand thermal volatility for the first shield 164.

FIG. 4 illustrates a cross-section view line representation of a portionof an example data reader 190 configured to mitigate magnetic andthermal volatility in the first shield 164 in accordance with someembodiments. The first shield 164 is configured with a fixed stabilizingmagnetization 192 that can be the same, or different than the fixedmagnetization 194 of the second shield 166. The fixed stabilizingmagnetization 194 can be set by at least one high temperature annealingoperation and maintained during operation by coupling the front shieldportion 180 to the second shield core 182 via a shield biasing structure196. The shield biasing structure 196 is constructed with a pinningantiferromagnetic (AFM) layer 198 contacting a ferromagnetic layer 200and setting the fixed stabilizing magnetization 200.

A shield coupling structure 202 is disposed between the front shield 180and the shield biasing structure 196. The shield coupling structure 202can be tuned for material, thickness along the Y axis, and position tomaintain the stabilizing magnetization 192 strength and orientationrelative to the ABS. The shield stabilizing structure 202 can be asingle layer of magnetic material, such as CoFe with a range ofcompositions like 30% Co by weight, a single layer of non-magneticmaterial, such as Ru, or a lamination of magnetic and non-magneticmaterials, such as a CoFe/Ru/CoFe configuration. The ability to tune theshield coupling structure 202 increases the reliability and strength ofcoupling with the shield biasing structure 196.

As shown, the second shield 166 consists of a shield biasing structure204 that contacts and is coupled to a shield core 206 with a stripeheight 208 extending from the ABS. The shield biasing structure 204 canbe a single magnetic layer or a lamination of layers, such as asynthetic antiferromagnet (SAF), that has the set stabilizingmagnetization 194 that may be set via one or more high temperatureannealing operations.

Construction of the shield coupling structure 202 mitigates the presenceof any residual pinning structure seed layer 186 material. It iscontemplated that some, or all, of the shield coupling structure 202extends from the ABS to separate the front shield portion 180 from thepinning 170 and shield biasing 196 structures with a front surface 210canted at a non-normal angle with respect to the ABS. However, suchconfiguration is not required or limiting as a separate dielectricbuffer layer 212 can be positioned between the pinning structure 170 andthe front shield portion 180. It is noted that the front shield portion180 has a reduced stripe height 214 compared to the stripe heights 196and 216 of the first shield 164 and biasing structure 202, respectively.

In some embodiments, the second shield stabilizing structure 208 isconfigured to provide ferromagnetic coupling while other embodimentsarrange the stabilizing structure 208 to maintain antiferromagneticcoupling between the front shield portion 180 and the biasing structure202. The stabilizing structure 208 may concurrently set the secondshield core 182 to the fixed stabilizing magnetization 200 orientedparallel to the magnetization of the front shield portion 180,perpendicular to the ABS, as dictated by one or more annealingoperations. A non-limiting example configures the second shieldstabilizing structure 208 as a single layer of magnetic material, suchas CoFe or NiFe, that continuously extends from the ABS to the bufferlayer 212 to provide an interface between the front shield portion 180and the biasing structure 202 conducive to maintaining ferromagneticcoupling strength and orientation.

FIG. 5 displays a cross-section line representation of a portion of anexample data reader 220 arranged with a coupling structure 222configured in accordance with various embodiments to maintainantiferromagnetic coupling between the front shield portion 180 and thebiasing structure 202. The coupling structure 222 has a non-magneticlayer 224 disposed between first 226 and second 228 magnetic layers. Thenon-magnetic layer 224 can be a diverse variety of materials, such as atransition metal, that continuously extends from the ABS around thefront shield portion 180 to the front surface 210 to form the bufferlayer 212, as shown.

The respective stabilizing magnetic layers 226 and 228 can be tuned tobe similar or dissimilar materials, sizes, and thicknesses along the Yaxis to ensure antiferromagnetic coupling and the maintenance of thefixed magnetization 200 strength and orientation in the front shieldportion 180. In the non-limiting embodiment shown in FIG. 5, the firstmagnetic layer 226 has a different thickness 230 and stripe height 232than the second magnetic layer 228.

The ability to tune the respective magnetic layers 226 and 228 to havelarger or smaller thicknesses and stripe heights allows the couplingstructure 222 to be more efficiently constructed and theantiferromagnetic coupling between the front shield portion 180 and thebiasing structure 202 to be controlled so as not to degrade in responseto encountered stray magnetic fields. It is further contemplated thatthe coupling structure layers are tuned to provide coupling that doesnot affect the fixed magnetization 174 of the pinning structure 170.

The second magnetic layer 228, as shown, has a stripe height 234 thatcontinuously extends from the ABS to contact the pinning structure 170and serve as a seed layer for the pinning layer 236 of the pinningstructure 170 while magnetically separating the biasing structure 202from the pinning layer 236. It is noted that the tuned stripe height 234and thickness 238 configuration of the second magnetic layer 228 can beselected with respect to the size and shape of the non-magnetic layer224 to prevent ferromagnetic coupling and maintain antiferromagneticcoupling between the front shield portion 180 and the biasing structure202.

It is noted that the non-magnetic layer 224 can continuously extend fromthe ABS up to the buffer layer 212. Various embodiments configure thenon-magnetic layer 224 to continuously wrap around the front shieldportion 180 to form the buffer layer 212 and define the front surface210. Such wrap around non-magnetic layer 224 configuration can have oneor more contacting sub-layers that are similar, or dissimilar,non-magnetic materials, such as alumina or a transition metal.

FIG. 6 illustrates a cross-sectional line representation of a portion ofan example data reader 250 arranged in accordance with assortedembodiments to mitigate magnetic volatility in a front shield portion180 of a shield 164. As displayed, the biasing structure 202 has beenpositioned proximal the ABS with a truncated stripe height 252 comparedto the embodiment shown in FIG. 5. The shorter stripe height 252 allowsthe first coupling structure 254 to continuously extend from the ABS toseparate the front shield portion 180 and biasing structure 202 from theshield core 256 as well as the pinning structure 170 while defining thefront surface 210.

It is contemplated that the shortening of the biasing structure's stripeheight 252 can localize the biasing magnetization to the ABS anddecrease the risk of magnetic volatility in the pinning structure 170.Positioning the biasing structure 202 proximal the ABS also allows thefirst coupling structure 254 to be tuned to provide predeterminedcoupling with the shield core 256. In other words, the first couplingstructure 254 can be a single layer of magnetic or non-magneticmaterial, in some embodiments, or a lamination of magnetic andnon-magnetic layers in other embodiments to control how magnetization258 from the biasing structure 202 affects the shield core 256.

A second coupling structure 260 may complement the first couplingstructure 254 by providing ferromagnetic or antiferromagnetic couplingwith the front shield portion 180. For example, the second couplingstructure 260 can be arranged with similar, or dissimilar, numbers ofconstituent layers, materials, thicknesses, and stripe heights than thefirst coupling structure 254 to maintain the fixed front shieldmagnetization 200 despite encountering stray magnetic fields and variousdata bit magnetizations during operation.

The capability of tuning the shape and size of the biasing structure 202along with the first 254 and second 260 coupling structures allows thedata reader 250 to have customized and independent fixed magnetizationsin the front shield portion 180, pinning structure 170, and shield core256, which can provide optimized data sensing performance whileproviding a reduced SSS 168. However, a tuned coupling structure is notlimited to the embodiments shown in FIGS. 3-6.

FIG. 7 depicts a cross-section line representation of a portion of anexample data reader 280 that employs a bias coupling structure 282 inaccordance with various embodiments to tune the magnetic coupling withina biasing structure 202. That is, when a biasing structure 202 isconfigured as a SAF, a bias coupling structure 282 can be positionedbetween first 284 and second 286 ferromagnetic layers to control thestrength and orientation of fixed bias magnetizations 288. The biascoupling structure 282 can be a single layer of non-magnetic material,such as Ru, Ta, or Cr, that has a thickness 290 tuned to maintain thefixed bias magnetizations 288 in predetermined orientations, such asperpendicular to the ABS.

The bias coupling structure 282 shown in FIG. 7 in accordance with someembodiments is a lamination of a non-magnetic sub-layer 292 disposedbetween first 294 and second 296 magnetic sub-layers, such as CoFe orNiFe. Although not required or limiting, the bias coupling structure 282can have a transition metal non-magnetic sub-layer 292 contacting asingle magnetic sub-layer, such as CoFe. Regardless of the number ofmagnetic sub-layers 294/296, the thickness of the non-magnetic sub-layer292 can be greater than each magnetic sub-layer 294/296 to tune thecoupling strength between the ferromagnetic layers 284 and 286 whilemaintaining antiferromagnetic coupling instead of exchange coupling, asindicated by the opposite magnetic orientations of the respectiveferromagnetic layers 284 and 286.

The ability to tune the coupling characteristics in a SAF biasingstructure 202 can be employed alone or in combination with one or moretuned coupling structures, such as 254 and 260, to provide sufficientcoupling between magnetic materials in the shield 166 without degradingthe fixed magnetization 174 of the pinning structure 170. As a result, adata reader can have multiple fixed magnetizations 174, 200, 258, and288 that are concurrently maintained at different orientations viaferromagnetic and/or antiferromagnetic coupling without inducingmagnetic volatility for the magnetoresistive stack 132 or shield 164.

It is noted that while various embodiments are directed to positioningthe front shield portion 180, biasing structure 202, and couplingstructure(s) 208, 222, 254, and 260 below the magnetoresistive stack132, such arrangement is not required. For instance, one or more biasingand stabilizing structures can be employed in a shield positioneddowntrack from the magnetoresistive stack 132. Hence, the use of theassorted aspects of the shield 164 is not limited to an uptrack positionand can be employed in any shield about a data reader or a data writer.

FIG. 8 provides a flowchart of an example data reader fabricationroutine 300 that may be carried out in accordance with some embodiments.Initially, a shield core is formed on a substrate in step 302. Theshield core can be magnetic and can be shaped with a varying thicknessto provide a notch on the ABS. Design decision 304 determines if abiasing structure is to be shaped to be localized to the ABS, asillustrated by data reader 250. Decision 304 is not dependent on anyprocess outcome of earlier steps of routine 300.

If a shaped biasing structure is chosen, step 306 creates a firstcoupling structure on the shield core, such as coupling structure 254,which may consist of one or more layers of magnetic or non-magneticmaterial to provide ferromagnetic or antiferromagnetic coupling betweenthe shield core and a biasing structure deposited in step 308.

It is noted that step 308 is executed even when decision 304 chooses notto shape the biasing structure. However, the biasing structure of step308 when the biasing structure is not shaped will have a greater stripeheight than when step 308 is executed after step 306. The biasingstructure can be configured as a SAF, as shown in data reader 220, or asa pinning lamination, as shown in data reader 190. With the biasingstructure constructed, step 210 patterns the biasing structure byremoving portions that are distal to the ABS, which may be subsequentlyfollowed by formation of a buffer layer or a buffer portion of the firstcoupling structure.

Atop the biasing structure, a coupling structure is formed in step 312.The coupling structure can be a single non-magnetic layer or acombination of magnetic and non-magnetic sub-layers to maintain eitherferromagnetic or antiferromagnetic coupling between the biasingstructure and a front shield portion created in step 314. In someembodiments, the constituent layers of the coupling structure are tunedto be different thicknesses, stripe heights, and/or materials to controlthe reliability and strength of coupling. The tuning of the coupling canreduce magnetic volatility in the shield without affecting the referencepinning magnetization provided by the pinning structure deposited instep 316.

The position of the pinning structure can be tuned to be aligned withthe front shield portion created in step 314, which reduces the SSS ofthe magnetoresistive (MR) stack formed in step 318. Routine 300 thencreates a downtrack shield atop the MR stack in step 320, which can beany number of layers, materials, and fixed magnetizations. It is notedthat the various steps of routine 300 may consist of the deposition andremoval of portions of several different materials and layers. Forexample, formation of the coupling structures in step 306 and 312 caninvolve successive deposition of non-magnetic and magnetic materials. Assuch, the various steps and decision of routine 300 are not required orlimiting as any portion can be changed or removed just as any step ordecision can be inserted.

Through the incorporation of one or more coupling structures into a datareader with a recessed pinning structure, fixed magnetizations in atleast one shield are reliably maintained via tuned coupling. The abilityto tune a coupling structure for the number of constituent layers,materials, and thicknesses allows a front shield portion to couple to ashield biasing structure to maintain a fixed shield magnetization in apredetermined direction regardless of encountered stray magnetic fieldsand operation of an adjacent magnetoresistive stack. The coupling in ashield can be selected to be ferromagnetic or antiferromagnetic, whichprovides diverse shield configurations that can be tuned to be conduciveto a wide variety of data densities and magnetoresistive stackarrangements.

It is to be understood that even though numerous characteristics ofvarious embodiments of the present disclosure have been set forth in theforegoing description, together with details of the structure andfunction of various embodiments, this detailed description isillustrative only, and changes may be made in detail, especially inmatters of structure and arrangements of parts within the principles ofthe present technology to the full extent indicated by the broad generalmeaning of the terms in which the appended claims are expressed. Forexample, the particular elements may vary depending on the particularapplication without departing from the spirit and scope of the presentdisclosure.

What is claimed is:
 1. An apparatus comprising a magnetoresistive stackpositioned on an air bearing surface (ABS), a portion of themagnetoresistive stack set to a first fixed magnetization by a pinningstructure separated from the ABS by a front shield, the front shield setto a second fixed magnetization by a biasing structure, the front shieldseparated from the biasing structure by a coupling structure.
 2. Theapparatus of claim 1, wherein the magnetoresistive stack comprises amagnetically free structure having a first stripe height as measuredperpendicular to the ABS and a magnetically fixed structure set to thefirst fixed magnetization and having a second stripe height from theABS, the first stripe height being smaller than the second stripeheight.
 3. The apparatus of claim 1, wherein the pinning structure isseparated from the front shield by a non-ferromagnetic transition metallayer.
 4. The apparatus of claim 1, wherein the pinning structure has afront surface proximal the ABS, the front surface canted at a non-normalangle with respect to the ABS.
 5. The apparatus of claim 1, wherein thecoupling structure comprises CoFe.
 6. The apparatus of claim 1, whereinthe coupling structure comprises NiFe.
 7. The apparatus of claim 1,wherein the coupling structure continuously extends from the ABS toseparate the front shield from the biasing structure and the pinningstructure.
 8. The apparatus of claim 1, wherein the second fixedmagnetization is orthogonal to the first fixed magnetization.
 9. Theapparatus of claim 1, wherein the coupling structureantiferromagnetically couples the front shield to the biasing structure.10. The apparatus of claim 1, wherein the coupling structureferromagnetically couples the front shield to the biasing structure. 11.An apparatus comprising: a magnetoresistive stack positioned on an airbearing surface (ABS); a first pinning structure contacting themagnetoresistive stack to set a portion of the magnetoresistive stack toa first fixed magnetization; and a front shield separating the firstpinning structure from the ABS, the front shield set to a second fixedmagnetization by a biasing structure, the front shield separated fromthe biasing structure by a first coupling structure comprising first andsecond coupling sub-layers.
 12. The apparatus of claim 11, wherein asecond pinning structure of the biasing structure sets the second fixedmagnetization.
 13. The apparatus of claim 12, wherein the second pinningstructure comprises a synthetic antiferromagnet (SAF).
 14. The apparatusof claim 13, wherein a second coupling structure is disposed betweenfirst and second ferromagnetic layers of the SAF, the second couplingstructure comprising a non-magnetic material disposed between first andsecond magnetic materials.
 15. The apparatus of claim 12, wherein thesecond pinning structure is disposed between the coupling structure anda shield layer.
 16. The apparatus of claim 11, wherein the firstcoupling sub-layer is non-magnetic and the second coupling sub-layer ismagnetic.
 17. The apparatus of claim 11, wherein the first couplingsub-layer is a transition metal material and is disposed between thesecond coupling sub-layer and a third coupling sub-layer, the second andthird coupling sub-layers each being a common magnetic material.
 18. Theapparatus of claim 17, wherein the common magnetic material comprisesCoFe.